Chapter 30, Problem 22A

Summary Introduction

Introduction:

The mammals are the organism that carry the babies in their wombs and give birth to the young ones. In initial days, the young ones are fed by the milk produced in the mammary glands of these organism. Although some of the mammals are also egg laying, they are called monotremes.

Answer to Problem 22A

Correct answer:

Option (C).

Explanation of Solution

Explanation/justification for the correct answer:

Option (C) echidna. Echidnas are monotremes. The monotremes are the mammals, which do not give birth to the young ones, instead they lay eggs like other animals. They evolved after early mammals, that evolved before marsupials and placental mammals. Hence, the correct answer is option (C).

Explanation for incorrect answer:

Option (A) elephant. The elephant is a placental mammals, which evolved recently in terms of evolution.

Option (B) opossum. They are furry animals native to America, they belong to the group of marsupial mammals. They evolved after monotremes. Hence, it is an incorrect answer.

Option (D) blue whales. They are also evolved after monotremes. Hence, it is an incorrect answer.